If the drive's not spinning up it's likely that it's either died completely or a connection inside the enclosure has been jarred loose. If the HDD's dead, I agree with the above that data recovery is going to be expensive. If it's a broken connection you may be able to get it repaired.

You have two ways of going about this. You canA: Break the enclosure case and take out the drive. (That is if the drive is still good) You can go to BestBuy or Wal-Mart or even online and buy a USB to SATA/IDE adapter. Once done, you can plug the IDE/SATA drive into your PC VIA USB and retrieve your data.
The problem with this is, you void your warrianty.

If you take the drive to BestBuy they will do this exact same thing for $200 (I know I use to do it lol)
Now, if the drive is bad, you can get what is called bit data recovery, which is where the head quarters for Geek Squad (GS) takes each bit of data one by one and tries to restore it but this can cost from $300 - $5000. Yes, $5000.

B: The warrianty on the external does not cover accidental damage, therefore if it is physically cracked etc it will not be covered. If luckily it's not you can send the drive back and get a replacement but just be advised your data is going to them and who knows what happened with it (It should be fine but you never know)

If it were me: I'd eat the cost of it, break the case and buy an IDE/SATA adapter and see if it works. Worst case you can just return the adapter back to the store.